I have a 14.5 hp 42'' twin blade riding lawn mower?

Well, It's a briggs and stratton engine with a Walbro carburetor
so I'd check and listen for a click to come from the botttom of the carburetor when the key is put in the on position. if no click is heared then change the silanoid on the bottom of the carb, or try to clean it out. Your mower wont throttle up because the plunger is still blocking the main jet.

legends small engine
April 2008